Wet brake systems have been implemented into a rear axle design of a machine or tractor for several years. In these systems, one or more brake disks is disposed between reaction plates. The disk rotates at axle speed and pressure can be applied to the disk by a piston to control the speed of the machine or tractor.
In the wet brake system, the one or more brake disks can be partially submersed in a bath of oil so that as the disk rotates oil flow is induced through a groove defined in the disk. A conventional brake disk can be formed of an inner metal core with a paper-like material disposed on both sides of the core. The groove in the brake disk can part of an overall groove pattern defined in the paper of the disk. The groove pattern can have a depth equal to or less than the overall thickness of the paper. As the brake disk rotates, the oil can flow from an inner diameter of the disk towards the other diameter thereof. As the oil flows from the inner diameter to the outer diameter, heat can be transferred and removed from the brake disk. In effect, heat that is generated when the brake disk is applied can be substantially removed to protect the integrity of the brake disk in the system.
Unfortunately, while many conventional brake disks have groove patterns that can remove heat therefrom, the disks have other limitations. For instance, referring to FIG. 1, a conventional brake disk 100 includes an outer layer of paper 102. A square-cut groove pattern 104 is defined in the paper layer 102 and includes a plurality of horizontal grooves 112 and a plurality of vertical grooves 114. As shown, some of the plurality of horizontal grooves 112 and vertical grooves 114 extend from an inner diameter 106 to an outer diameter 108 of the disk 100. However, there are several horizontal and vertical grooves that do not extend between the inner diameter 106 and outer diameter 108. For instance, horizontal groove 118 and vertical groove 116 extend from one location at the outer diameter 108 to a second location at the outer diameter 108.
As the brake disk rotates, oil is able to flow from the inner diameter 106 to the outer diameter 108 through only a limited number of grooves. In this manner, the brake disk 100 includes some grooves that are optimally positioned to receive and transfer oil through the disk and other grooves that are not optimally positioned to achieve the same. As a result, the brake disk 100 may include zones of entrapped air where oil or other fluid cannot flow or there is reduced flow. In cases of entrapped air, there is a lack of heat transfer through the disk thereby forming hot pockets on the disk and possible damage or defects to the disk due to heat.
Another problem with the brake disk of FIG. 1 is its lack of a separation or centering feature. During a braking event, the brake disk 100 is engaged by separator plates that are disposed on both sides of the disk. As the brake is released, the piston releases pressure against the separator plates. However, the brake disk 100 does not include a separation feature for hydraulically separating the disk 100 from the separator plates. Thus, the brake disk 100 can drag with the separator plates and cause a reduction in power performance of the machine or tractor.
To overcome drag, some conventional brake disks include a separation feature. In FIG. 2, for example, a conventional brake disk 200 is shown that includes a metal core and a paper layer 202. The paper layer 202 defines a square-cut groove pattern 204 between the inner diameter 206 and outer diameter 208 of the disk 200. The square-cut groove pattern 204 defines a plurality of squares 210 formed by a first groove 212 and a second groove 214. The first groove 212 and second groove 214 are perpendicular to one another. Similar to the groove pattern 104 of the first convention disk 100, the second groove pattern 204 of disk 200 also includes some grooves that intersect both the inner diameter 206 and outer diameter 208 and other grooves that only intersect the outer diameter 208. As a result, the brake disk 200 has certain areas that are better at transferring heat from the disk and others that are not.
The brake disk 200 also includes six slots 216. Each slot 216 forms an inlet portion 218 at the inner diameter 206 and includes a dead-end or closed portion 220 near the outer diameter 208. The dead-end or closed portion 220 does not intersect the outer diameter 208, so oil or other fluid flowing through the slot 216 builds therein. Thus, when the brake is released, the buildup of oil or fluid in each slot 216 causes the brake disk 200 to hydraulically separate from the separator plates. The dead-end or closed portion 220 of each slot 216, however, causes a lack of heat transfer and prevents the brake disk 200 from cooling.
Therefore, it would be desirable to provide a brake disk with a groove pattern that can effectively promote heat transfer and hydraulically separate the brake disk from separator plates.